NORTH PACIFIC LAND BRIDGE 329 



early Tertiary marine faunas to those of California would 

 thus receive a satisfactory explanation without invoking a 

 land connection across Bering Strait. As soon as the marine 

 channel which separated the coast hills in California from the 

 rest of the country disappeared, a number of Asiatic immi- 

 grants entered North America. But the flora, especially of the 

 small islands lyi,ng off the coast of California, still bears the 

 impress, as Mr. Greene* has pointed out, of belonging phyto- 

 geographically to another continent than America. 



I also mentioned that the European invasion of North 

 America, which travelled by the trans-Atlantic land bridge, 

 had ultimately entered the Continent from the south-west. 

 The two elements, the Asiatic and the European, must have 

 joined there eventually. To judge from purely faunistic testi- 

 mony, that was evidently the course of events (compare 

 p. 211) . Somewhere about the Miocene Period extensive sub- 

 sidence of the land west of California must have compelled 

 the fauna and flora to seek refuge on the continent with which 

 the Pacific belt of land seems to have become united. Palaeon- 

 tological evidence gives us reason for such a supposition. Take 

 for example the great land-tortoises. Their sudden appearance 

 in south-western Miocene deposits suggests that they came 

 from the west with other new-comers. This hypothesis like- 

 wise throws light on their survival near at hand in the Gala- 

 pagos islands, which no doubt once fonned part of the Pacific 

 belt of land alluded to. There are such a variety of problems 

 connected with this theory that I shall defer the further dis- 

 cussion of it till the next chapter. In conclusion, a few addi- 

 tidnal remarks on the nature of the supposed extension of land 

 west of Central America will facilitate the comprehension of 

 the scheme of land connections that have only been roughly 

 outlined so far. 



When I described the remarkable fauna and flora of the 

 Cape region of Lower California (p. 207) and their majked 

 affinities to those of the opposite coast of Mexico, I made no 

 reference to the fact that this interesting assemblage of 

 animals and plants is living in a hilly district being separated 

 from the nearest mountains to the north of it by a wide extent 



* Greene, E. L., " Botany of Santa Cruz Island," pp. 377—388. 



